EFFECT OF BLENDED (NPSB) FERTILIZER RATE ON GROWTH AND YEILD OF ONION (Allium cepa L.) VARIETIES AT MIRAB ABAYA DISTRICT, GAMO ZONE, SNNPR OF ETHIOPIA

Abstract

Onion (Allium cepa, L.) is one of the most important vegetable crops grown in Ethiopia for consumption and sources of income for many small and large scale farmers. However, due to Nutrient management, lack of improved varieties, poor agronomic practices and pests are the most critical causes of low production and productivity of onion in Gamo Zone. Therefore, field experiment was carried out to the effect of blended (NPSB) fertilizer rates on the growth and yield of onion varieties in the Mirab Abaya district from December 2021 to June 2022 under irrigation. The experiment was laid out in randomized complete block design (RCBD) with three replications in 3x5 factorial arrangements: three onion varieties (Bombay Red, Red Creole and Melkam) and five levels of blended NPSB fertilizer rates (0, 150, 250, 350, and 450 kg ha-1). The data on growth and yield characteristics were collected for two rounds. The growth data was taken after four months and yield data was collected at time of harvest. The result revealed that the two main factors, variety and blended NPSB fertilizer rates had significant effect on all parameters considered in this study. The interaction of variety and blended NPSB fertilizer rates had significant effect on growth parameters (plant height, leaf length and leaf number), and yield parameters (bulb weight, marketable, unmarketable and total bulb yield). However, the interaction of two factors had non-significant effect on bulb length in yield parameter. Melkam variety was the beast one compere to Bombay Red and Red Creole variety in our growth and yield parameters. The application of 350 kgha-1 blended NPSB fertilizer rate was the beast in our growth and yield parameters. On the other hand, Melkam variety with the application of 350kg ha-1 blended NPSB rate fertilizer showed the highest marketable bulb yields and total bulb yields was 42.33tha-1 and 42.35tha-1 respectively. Furthermore, economic analysis indicated that Melkam variety with the application of 350kg ha-1 blended NPSB fertilizer rate resulted in the highest net benefit with acceptable marginal rate of return. Generally, application of 350kgha-1 blended NPSB fertilizer rate over Melkam onion variety would promote the growth and yield components of onion in the study area. However, the result of this study is from one season work and further specific field studies need to be conducted in different seasons across multi location for sound recommendation.